Delamination-resistant multilayer container preform, article and method with oxygen barrier formulations

ABSTRACT

A plastic preform, container or article includes a multilayer wall having at least one layer of a matrix resin, at least one layer of a barrier resin, an adhesion-promoting material blended with the barrier resin and/or matrix resin, and an active oxygen barrier composition blended with the barrier resin and/or matrix resin. The adhesion-promoting material promotes bonding between the barrier and matrix resin layers and includes an amine polymer, preferably an imine polymer having a number of available primary, secondary or tertiary amine groups. The matrix resin preferably is an ester-containing resin, such as PET. The barrier resin preferably is EVOH. The active oxygen barrier composition includes a metal with an additive compound, and may also include a host polymer.

The present invention is directed to multilayer plastic containers,preforms and articles of manufacture, and more specifically tomultilayer plastic containers and preforms that are resistant todelamination and provide a barrier to oxygen permeating through thelayers of the container/preform wall.

BACKGROUND OF THE INVENTION

Multilayer plastic containers and preforms typically include one or morelayers of plastic matrix resin, such as polyethylene terephthalate(PET), alternating with one or more layers of barrier resin such aspolyamide or polyethylene vinyl alcohol copolymer (EVOH) to resisttransmission of gas, water vapor and/or flavorants, including odorantsand essential oils, through the container wall. Interlaminar adhesionamong the several layers of the multilayer wall is necessary in order toresist delamination of these layers and to enhance barrier properties.Furthermore, the plastic material of the matrix layers typically issusceptible to relatively high permeation of substances such as oxygen,carbon dioxide and water through its polymeric/molecular structure.Permeation of these substances, particularly oxygen, can deteriorate thequality of the contents of the product packaged within the container.

In U.S. application Ser. No. 10/688,432, interlaminar adhesion betweenthe several layers of a multilayer plastic container/preform wasimproved by incorporating at least one layer of a matrix resin, at leastone layer of a barrier resin, and an adhesion-promoting material blendedwith the barrier and/or the matrix resin in the container/preform wall.The matrix resin included an ester-containing resin, preferably apolyester such as PET. The adhesion-promoting material included an aminepolymer having a number of available primary, secondary and tertiaryamine groups. The barrier resin included EVOH or polyamide.

In U.S. Provisional Application 60/473,024, an active oxygen barriercomposition was used to retard oxygen from permeating through amultilayer plastic wall. These active oxygen barrier compositionsincluded one or more polymers and low molecular weight additives. Theactive oxygen barrier composition included a metal, an additivecompound, and possibly a host polymer.

What is needed is a combination of both an adhesive-promoting materialand an active oxygen barrier composition in the barrier layer and/ormatrix layer of the multilayer plastic container/preform wall that iseffective and achieves desirable results. Thus, it is an object of thepresent invention to provide a multilayer plastic container, preform orarticle of manufacture having suitable interlaminar adhesion between theseveral layers of the multilayer wall and has a high barrier againstpermeation of oxygen therethrough.

SUMMARY OF THE INVENTION

In a preferred aspect of the present invention, a plastic preform,container or article of manufacture includes a multilayer wall having atleast one layer of a matrix resin, at least one layer of a barrierresin, an adhesion-promoting material blended with the barrier resinand/or matrix resin, and an active oxygen barrier composition blendedwith the barrier resin and/or matrix resin. The adhesion-promotingmaterial promotes bonding between the barrier resin layer and the matrixresin layer, and the active oxygen barrier composition retardspermeation of oxygen.

The adhesion-promoting material is an amine polymer, preferably an iminepolymer, having a number of available primary, secondary or tertiaryamine groups. The imine polymer preferably is an alkylene imine polymeror an alkylene amine polymer. Alkylene imine polymers, particularlypolyethyleneimine (PEI) polymers are particularly preferred.

The matrix polymer preferably is an ester-containing polymer or anysuitable polyester resin having an ester in the main polymer chain.Suitable polyesters include polyethylene terephthalate (PET),polybutylene terephthalate (PBT), polypropylene terephthalate (PPT),polyethylene naphthalate (PEN), polyglycolic acid (PGA), polycarbonate(PC) and polylactic acid (PLA). Other suitable matrix polymers includepolyacrylates, such as polymethyl methacrylate (PMMA), polyethylenemethacrylate (PEMA) and vinyl acetates. Also blends or copolymers of theabove including process and post-consumer regrind that consistsessentially of the above, where PET-based resins, blends, copolymers andregrinds are particularly preferred. Other matrix polymers may alsoinclude polyolefins and polyamides.

The barrier resin preferably is selected from the group consisting ofEVOH, polyamide, acrylonitrile copolymers, blends of EVOH and polyamide,nanocomposites of EVOH or polyamide and clay, blends of EVOH and anionomer, acrylonitrile, cyclic olefin copolymers, polyvinylidenechloride (PVDC), polyglycolic acid (PGA), and blends thereof. EVOH isparticularly preferred.

The active oxygen barrier composition includes a metal and a compoundcomprising the structure

The moiety -E is selected from the group consisting of —C(═O)H, —CH₂R¹and —CHR¹R²; wherein R¹ is —O—R³—R⁴ or —O—R⁴, such that R¹ comprises atleast 2 carbon atoms and does not contain a carbonyl group, and R³ andR⁴ are independently selected from the group consisting of alkyl,alkenyl, alkynyl, heteroalkyl, aryl and heterocyclic; R² is —O—R⁵—R⁶ or—O—R⁶, such that R² comprises at least 2 carbon atoms and does notcontain a carbonyl group, and R⁵ and R⁶ are independently selected fromthe group consisting of alkyl, alkenyl, alkynyl, heteroalkyl, aryl andheterocyclic; or R¹ and R², together with the atoms to which they arebonded, form a ring comprising from 5 to 20 ring atoms.

In accordance with another aspect of the present invention, a method ofmaking a multilayer plastic article includes blending with the barrierresin an adhesion-promoting material comprising alkylene amine polymersand an active oxygen barrier composition as described above. Themultilayer wall of the preform is formed by incorporating theadhesion-promoting material blend and the active barrier composition inlayers alternating with layers of a matrix polymer, or resin, as alsodescribed above.

The invention thus provides improved adhesion between the barrier andthe matrix layers of the multilayer wall to reduce delamination of thelayers during handling and use of the containers. The invention furtherenhances retardation of oxygen permeation through the several layers ofthe multilayer wall.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objects, features, advantagesand aspects thereof, will be best understood from the followingdescription, the appended claims and the accompanying drawings in which:

FIGS. 1A and 1B are schematic diagrams of a container preform inaccordance with one aspect of the present invention,

FIGS. 2A and 2B are schematic diagrams of a plastic container inaccordance with another aspect of the present invention,

FIGS. 3 through 7 are graphic illustrations of test results oncontainers fabricated in accordance with exemplary embodiments of thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides a multilayer plastic container, preformor article including an adhesion-promoting material and an active oxygenbarrier composition in the multilayer wall. The wall has several layersincluding at least one layer of a matrix resin, at least one layer of abarrier resin. Preferably, the barrier resin is a thermoplastic resin,such as EVOH, and the matrix resin is an ester-containing resin, such atPET. The adhesion-promoting material is blended with the barrier resinand/or the matrix resin for bonding between the two layers. Theadhesion-promoting material is an amine polymer, preferably an iminepolymer having a number of available primary, secondary and tertiaryamine groups. The active oxygen barrier composition is incorporated intothe matrix resin and/or the barrier resin layers. The active oxygenbarrier composition includes a metal with an additive compound and mayalso include a host polymer.

In accordance with one aspect of the present invention, the multilayerwall has at least one layer of the matrix resin (also referred tothroughout this application as a polyester resin) alternating with atleast one layer of the barrier resin, which may contain the activeoxygen barrier material. For example, a three-layer wall may have alayer sequence of polyester/barrier/polyester. A five-layer wall mayhave a layer sequence of polyester/barrier/polyester/barrier/polyester.Post-consumer resin layers may also be included in the multilayerstructure. An illustrative depiction of a five-layer preform for blowmolding a plastic container is shown in FIGS. 1A and 1B. Likewise, anillustrative depiction of a five-layer container is shown in FIGS. 2Aand 2B. For either the preform (shown in FIGS. 1A and 1B) or thecontainer (shown in FIGS. 2A and 2B), the barrier layer or layers mayextend throughout the bottom wall and the sidewall of the container orpreform, or may be confined to a portion of the sidewall or base. Alsothe barrier layers may or may not extend into the neck finish of thecontainer or preform.

The barrier resin preferably is a thermoplastic material that has a lowgas and/or water vapor transmission rate and/or exhibits a highbarrier-to-transmission of flavorants including odorants and essentialoils. The following barrier resin materials are preferred: EVOH,polyamide (including amorphous polyamide and semicrystalline polyamidesuch as MXD6), acrylonitrile copolymers, blends of polyester (e.g., PET)and polyamide, blends of EVOH and an ionomer, cyclic olefin copolymers,PGA, nanocomposites of EVOH or polyamide and clay, polyvinylidenechloride, and blends thereof. EVOH and polyamide are particularlypreferred. EVOH is employed as a barrier resin in the examples discussedin this invention. One or more other barrier compositions may also beemployed.

The matrix resin, or polymer, is preferably an ester-containing polymeror any suitable polyester resin having an ester in the main polymerchain. Suitable polyesters include polyethylene terephthalate (PET),polybutylene terephthalate (PBT), polypropylene terephthalate (PPT),polyethylene naphthalate (PEN), polyglycolic acid (PGA), polycarbonate(PC) and polylactic acid (PLA). Also, the matrix polymers may includepolyacrylates, such as polymethyl methacrylate (PMMA), polyethylenemethacrylate (PEMA) and vinyl acetates, polyolefins and polyamides. Thematrix resin of the present invention preferably is selected from thegroup consisting of PET, PEN, blends and copolymers of PET and PEN, andprocess or post consumer regrind that consists essentially of PET, PEN,or blends or copolymers of PET and PEN. In the examples discussed in thepresent invention, the resin is PET-based polyester.

The adhesion-promoting material used in the examples of the presentinvention is blended with the barrier resin (EVOH). As disclosed in U.S.application Ser. No. 10/688,432, which is herein incorporated byreference, the adhesion-promoting material preferably includes analkylene amine polymer, of which an alkylene imine polymer is preferred,particularly a polyethyleneimine (PEI) polymer. Particularly preferredPEI polymers are EPOMIN (trade name) grade SP-012 polymers manufacturesby Nippon Shokubai Co., Ltd. Other PEI polymers may be employed,including other EPOMIN polymers and PEI polymers marketed by other resinmanufactures such as BASF under the trade name LUPASOL.

It is preferred that the adhesion-promoting material be blended with thebarrier resin. Because the barrier resin layers form a relatively smallpercentage by weight of the overall preform or container, a lesserquantity of adhesion-promoting material is required than if theadhesion-promoting material is blended with the matrix resin. However,the adhesion-promoting material could be blended with the matrix resin,or with both the matrix resin and the barrier resin.

The amount of adhesion-promoting resin preferably is no more than whatis necessary to achieve the desired level of adhesion, as increasing theproportion of adhesion-promoting material may affect the viscosity orother properties of the resin with which it is blended. The amount ofadhesion-promoting material blended with the barrier resin or the matrixresin preferably does not exceed about 10%, and more preferably does notexceed 5% by weight of the blend used to form the multilayer article. Inthis regard, the adhesion-promoting material preferably is blended witha barrier resin, and preferably does not exceed about 10% by weight ofthe blend. The amount of adhesion-promoting material more preferablydoes not exceed about 5% by weight of the blend with the barrier resinused to form the multilayer articles. In many applications, the amountof the adhesion-promoting material does not exceed 2% or 3% by weight ofthe blend with the barrier resin. All blend percentages in thisapplication are by weight unless otherwise indicated.

The active oxygen barrier composition is also incorporated into theplastic layers of the multilayer wall to provide an active oxygenbarrier. An “active oxygen barrier” refers to a material having theability to consume oxygen through chemical and/or physical means. An“active composition” refers to a substance which can be used as anactive oxygen barrier material. A “barrier material” is any materialthat retards permeation for a particular substance, such as oxygen orcarbon dioxide, in comparison to another material. Thus, an activeoxygen barrier material is one in which consumes oxygen through chemicaland/or physical means to retard the permeation of oxygen therethrough.Suitable compounds for the active oxygen barrier composition of thepresent invention are those disclosed in U.S. Provisional Application60/473,024, which is herein incorporated by reference.

The active oxygen barrier composition generally includes compoundscontaining structure (I):

where =A may be an alkenyl group having from 3 to 20 carbon atoms, acycloalkenyl group having from 5 to 20 carbon atoms, or ═CH-E, where -Emay be —CH₂OH, —CH(OH)₂, —C(═O)H, —CH₂R¹ or —CHR¹R², where R¹ may be—O—R³—R⁴ or —O—R⁴, and R² may be —O—R⁵—R⁶ or —O—R⁶; or R¹ and R²,together with the atoms to which they are bonded, form a ring.

Examples of “A” moieties where =A is an alkenyl group include propenyl;methyl propenyl; butenyl; methyl butenyl; pentenyl; methyl pentenyl;dimethyl pentenyl; ethyl pentenyl; hexenyl; methyl hexenyl; dimethylhexenyl; ethyl hexenyl; diethyl hexenyl; hexadienyl; methyl hexadienyl;dimethyl hexadienyl; ethyl hexadienyl; and diethyl hexadienyl. Forexample, the compound containing structure (I) and having a4-methyl-3,5-hexadienyl group as A is commonly referred to as“farnesene.” Examples of “A” moieties where =A is a cycloalkenyl groupinclude cyclopentenyl; methyl cyclopentenyl; ethyl cyclopentenyl;cyclohexenyl; methyl cyclohexenyl; ethyl cyclohexenyl; cyclohexadienyl;methyl cyclohexadienyl; ethyl cyclohexadienyl; cycloheptadienyl;cyclooctenyl; and cyclooctadienyl. For example, the compound containingstructure (I) and having a 4-methyl-3-cyclohexenyl group as A iscommonly referred to as “bisabolene.”

For compounds where =A is ═CH-E and -E is —CH₂R¹ or —CHR¹R², R¹ may be—O—R³—R⁴ or —O—R⁴, and R² may be —O—R⁵—R⁶ or —O—R⁶; or R¹ and R²,together with the atoms to which they are bonded, form a ring. Thegroups R³, R⁴, R⁵ and R⁶ may independently be alkyl, alkenyl, alkynyl,heteroalkyl, aryl or heterocyclic. Preferably, a ring containing R¹ andR² has from 5 to 20 ring atoms, more preferably from 5 to 10 ring atoms.These rings may be hydrocarbon rings or heterocyclic rings, may besubstituted or unsubstituted, may be fused to another ring, and may besaturated (i.e. cycloalkyl), unsaturated (i.e. cycloalkenyl), oraromatic (i.e. phenyl).

Preferably, the active oxygen barrier composition includes compoundscontaining structure (I) where =A is ═CH-E. Thus, preferred activebather compositions include compounds containing structure (II):

where -E may be —CH₂OH, —CH(OH)₂, —C(═O)H, —CH₂R¹ or —CHR¹R², where R¹may be —O—R³—R⁴ or —O—R⁴, and R² may be —O—R⁵—R⁶ or —O—R⁶; or R¹ and R²,together with the atoms to which they are bonded, form a ring. Thegroups R³, R⁴, R⁵ and R⁶ may independently be alkyl, alkenyl, alkynyl,heteroalkyl, aryl or heterocyclic. Preferably, a ring containing R¹ andR² has from 5 to 20 ring atoms, more preferably from 5 to 10 ring atoms.These rings may be hydrocarbon rings or heterocyclic rings, may besubstituted or unsubstituted, may be fused to another ring, and may besaturated (i.e. cycloalkyl), unsaturated (i.e. cycloalkenyl), oraromatic (i.e. phenyl).

Examples of —O—R⁴ and —O—R⁶ independently include alkoxy groups (R⁴ orR⁶ are C₁ to C₂₀ alkyl), such as methoxy, ethoxy, propoxy, cyclopropoxyand cyclohexoxy groups, and may be substituted. Examples of —O—R⁴ and—O—R⁶ independently include aryloxy groups (R⁴ or R⁶ are C₅ to C₂₀aryl), such as phenoxy, cresoxy, ethylphenoxy, cumyloxy, and naphthoxygroups, and may be substituted. Examples of —O—R³—R⁴ and —O—R⁵—R⁶independently include aryl-alkoxy groups (R³ or R⁵ are C₁ to C₂₀ alkyl,and R⁴ or R⁶ are C₅ to C₂₀ aryl), such as benzyloxy, 2-ethoxyphenyl andiso-propoxyphenyl groups, and may be substituted on the aryl and/oralkoxy moiety. Examples of —O—R³—R⁴ and —O—R⁵—R⁶ independently includearyl-aryloxy groups (R³ or R⁵ and R⁴ or R⁶ are independently C₅ to C₂₀aryl), such as cumylphenoxy, biphenoxy and benzylphenoxy groups, and maybe substituted on the aryl and/or aryloxy moiety. Examples of —O—R⁴ and—O—R⁶ independently include: heteroalkoxy groups (R⁴ or R⁶ are C₅ to C₂₀heteroalkyl), such as 2-methoxyethoxy, 2-ethoxyethoxy 2-ethoxyacetategroups, and may be substituted. Examples of —O—R⁴ and —O—R⁶independently include alkenoxy groups (R⁴ or R⁶ are C₂ to C₂₀ alkenoxy),such as propenoxy, butenoxy, isopropenoxy, pentadienoxy, cyclopentenoxy,cyclohexenoxy, oleyloxy, undecylenoxy, geranyloxy, farnesoxy andnerolidoxy groups, and may be substituted.

For compounds of the active oxygen barrier composition containingstructure (II) where R¹ and R², together with the atoms to which theyare bonded, form a ring, the compounds can be represented as structure(III):

The tertiary carbon atom positioned directly between R¹ and R² isreferred to herein as the “bridgehead” carbon. The closed ring is thusformed by the bridgehead carbon, R¹, R², and the other atoms between R¹and R². Examples of rings containing both R¹ and R² include ringscontaining the bridgehead carbon bonded to the group —R¹—R²—, where—R¹—R²— can be an alkyl group such as butyl (—C₄H₈—) or pentyl(—O₅H₁₀—); an alkenyl group such as butenyl or pentenyl; a heterocyclicgroup such as 1,4-butyl-di-oxy (—O—C₄H₈—O—), 1,4-butyl-di-oxy(—O—C₅H₁₀—O—), ethylene glycoxy (—O—C₂H₄—O—) and diethylene glycoxy(—O—C₂H₄—O—C₂H₄—O—); and an aryl group such as catechol(—O-(ortho-C₆H₄)—O—); and may be substituted. Thus, a ring containingbridgehead carbon and the group —R¹—R²— may be a cycloalkyl group, acycloalkenyl group, an aryl group, and a heterocyclic group. Forexample, if —R¹—R²— is a heterocyclic group, the ring may be similar toa crown ether, containing from 1 to 5 oxygen atoms, or preferablycontaining from 2 to 3 oxygen atoms; and containing from 3 to 9 carbonatoms, or from 2 to 6 carbon atoms.

The presence of one or more compounds of the present invention as anadditive in a polymer material can impart active oxygen barrierproperties to the composition. In the context of a closed environmentwith which the active composition, or material containing the activecomposition, is in contact, the consumption of molecular oxygen mayeliminate or substantially reduce the net ingress of oxygen into theenvironment. Moreover, the consumption of molecular oxygen may reducethe total enclosed amount of molecular oxygen.

Examples of compounds of the present invention include compoundscontaining structure (II) where -E is —CHR¹ (—O—R⁶), where R⁶ is analkyl group containing from 1 to 20 carbon atoms; where R⁶ is an alkenylgroup containing from 2 to 20 carbon atoms; and where R⁶ is an alkenylgroup containing from 4 to 20 carbon atoms and also having 2 or morecarbon-carbon double bonds.

Examples of compounds of the present invention include compoundscontaining structure (II) where -E is —CHR¹ (—O—R⁵—R⁶), where R⁵ is analkyl group containing from 1 to 20 carbon atoms; where R⁵ is an alkylgroup containing from 2 to 20 carbon atoms; where R⁵ is an alkenyl groupcontaining from 2 to 20 carbon atoms; and where R⁵ is an aryl groupcontaining from 5 to 20 carbon atoms. These examples further includecompounds where R⁶ is an alkyl group containing from 1 to 20 carbonatoms; where R⁶ is an alkyl group containing from 2 to 20 carbon atoms;where R⁶ is an alkenyl group containing from 2 to 20 carbon atoms; andwhere R⁶ is an aryl group containing from 5 to 20 carbon atoms. Theseexamples further include compounds where R⁵ is an alkyl group containingfrom 1 to 20 carbon atoms and R⁶ is an aryl group containing from 5 to20 carbon atoms. These examples further include compounds where R⁵ is anaryl group containing from 5 to 20 carbon atoms and R⁶ is an aryl groupcontaining from 5 to 20 carbon atoms.

Examples of compounds of the present invention include compoundscontaining structure (II) where -E is —CH₂(—O—R⁴), where R⁴ is an alkylgroup containing from 1 to 20 carbon atoms; where R⁴ is an alkenyl groupcontaining from 2 to 20 carbon atoms; and where R⁴ is an alkenyl groupcontaining from 4 to 20 carbon atoms and also having 2 or morecarbon-carbon double bonds.

Examples of compounds of the present invention include compoundscontaining structure (II) where -E is —CH₂(—O—R³—R⁴), where R³ is analkyl group containing from 1 to 20 carbon atoms; where R³ is an alkenylgroup containing from 2 to 20 carbon atoms; and where R³ is an arylgroup containing from 5 to 20 carbon atoms. These examples furtherinclude compounds where R⁴ is an alkyl group containing from 1 to 20carbon atoms; where R⁴ is an alkenyl group containing from 2 to 20carbon atoms; and where R⁴ is an aryl group containing from 5 to 20carbon atoms. These examples further include compounds where R³ is analkyl group containing from 1 to 20 carbon atoms and R⁴ is an aryl groupcontaining from 5 to 20 carbon atoms. These examples further includecompounds where R³ is an aryl group containing from 3 to 20 carbon atomsand R⁴ is an aryl group containing from 5 to 20 carbon atoms.

Examples of compounds of the present invention include compoundscontaining structure (II) where -E is —CH₂R¹ or —CH—R¹R², and R¹ and/orR² are moieties such as —OCH₃ (CDMA); —OCH₂CH₃ (CDEA);—OCH═C(CH₃)(CH₂)₂CH═C(CH₃)₂ (CDGA); and —OCH₂—C₆H₅ (CDBA).

Specific examples of compounds of the present invention that can be usedas additives include the following:

citral—structure (II), E is C(═O)H;

geraniol—structure (II), E is CH₂OH;

citral dimethyl acetal—structure (II), E is CH(OCH₃)₂;

citral diethyl acetal—structure (II), E is CH(OCH₂CH₃)₂;

citral dipropyl acetal—structure (II), E is CH(OCH₂CH₂CH₃)₂;

citral digeranyl acetal structure (II), E is

-   -   CH(OCH═C(CH₃)(CH₂)₂CH═C(CHs)₂)₂;        undecylenic aldehyde—structure (II),    -   digeranyl acetal E is CH₂(OCH(CH═CH(CH₂)₇CH₃)    -   (UADA) (OCH₂CH═C(CH₃)(CH₂)₂CH═C(CH₃)₂)        citral ethylene glycyl acetal—structure (II), E is a ring        designated (—R¹—R²—),    -   which is —O— (CH₂)₂—O—;        citral diethylene—structure (II), E is a ring designated        (—R¹—R²—),    -   glycyl acetal which is —O— (CH₂)₂—O— (CH₂)₂—O—;        citral dibenzyl acetal—structure (II), E is CH(OCH₂—C₆H₅)₂;        citral dicumylphenyl acetal—structure (II), E is        CH(OC₆H₄—C(CH₃)₂—C₆H₅)₂;        farnesene—structure (II), A is ═CHCH₂CH═C(CH₃)CH═CH₂;    -   and bisabolene—structure (I), A is 4-methyl-3-cyclohexene.

The preferred compounds of the active oxygen barrier composition arecompounds containing structure (II), where E is either an aldehyde(—C(═O)H) or is —CH₂R¹ or —CHR¹R², where at least one of R¹ or R² is anether group having at least two carbon atoms. These preferred compoundsinclude compounds where R¹ and R² form an ether-containing ring asdescribed above. Preferably, if E is —CH₂R¹ or —CHR¹R², neither R¹ norR² contain a carbonyl functionality (>C=0) or a terminal hydroxylfunctionality (—CH₂OH). Particularly preferred compounds of the presentinvention are compounds containing structure (II), where E is either analdehyde (—C(═O)H) or is —CH₂R¹ or —CHR¹R², where at least one of R¹ orR² is an ether group having at least three carbon atoms. Preferably, thecompounds of the present invention include citral, citral diethylacetal, citral digeranyl acetal, UADA, citral ethylene glycyl acetal,citral diethylene glycyl acetal, citral dibenzyl acetal, citraldicumylphenyl acetal, and bisabolene. Particularly preferred compoundsof the present invention include citral, citral digeranyl acetal, citralethylene glycyl acetal, citral diethylene glycyl acetal, citral dibenzylacetal, citral dicumylphenyl acetal, citral diethyl acetal and citraldimethyl acetal.

Metals that may be used with an additive compound of the active oxygenbarrier composition include transition metals. Examples of transitionmetals include iron, cobalt, nickel, ruthenium, rhodium, palladium,osmium, iridium, platinum, copper, manganese and zinc. The metal may beadded as a salt or complex with another element or chemical group. Forexample, the metal may be added as a complex with an organic ligand suchas a carboxylate, an amine, or an alkene. Examples of ligands which mayform complexes with the above transition metals include naphthenate,octoate, tallate, resinate, 3,5,5-trimethylhexoate, stearate, palmitate,2-ethylhexanoate, neodecanoate, acetate, butyrate, oleate, valerate,cyclohexanebutyrate, acetylacetonate, benzaylacetonate,dodecylacetylacetonate, benzoate, oxalate, citrate, tartrate,dialkyldithiocarbamate, disalicylalethylenediamine chelate, andphythalocyanine. Examples of specific metal complexes which may beuseful include cobalt (II) 2-ethylhexanoate, cobalt (II) neodecanoate,cobalt (II) acetate, and cobalt (II) oleate.

A polymeric material may be used as a host polymer to provide an activeoxygen barrier composition in combination with the compound of thepresent invention and the metal. Examples of host polymers includepolyolefins, such as polyethylene, polypropylene, polyisoprene,polybutadiene and polyvinyl alcohol); styrenic polymers, such aspolystyrene and poly(4-methylstyrene); polyacrylates, such aspoly(methyl acrylate), poly(ethyl acrylate), poly(methyl methacrylate),and poly(ethyl methacrylate); polyamides, such as nylon-6,6, nylon 6,nylon 11, and polycaprolactam; other nitrogen-containing polymers, suchas polyacrylamide, polyacrylonitrile and poly(styrene-co-acrylonitrile);halogenated polymers such as poly(vinyl chloride), poly(vinylidenechloride) and polytetrafluoroethylene; polyesters, such as poly(ethyleneterephthalate), poly(butylene terephthalate), 16 poly(ethylenenaphthalate), poly(lactic acid), and poly(glycolic acid);polycarbonates, such as poly(4,4′-isopropylidine-diphenyl carbonate);polyethers, such as poly(ethylene oxide), poly(butylene glycol),poly(epichlorohydrin), and poly(vinyl butyral); heterocyclic polymers,such as polyimides, polybenzimidazoles, polybenzoxazoles, and poly(vinylpyrrolidone); other engineering polymers such as polysulfones,poly(ether ether ketones), poly(phenylene oxide), and poly(phenylenesulfide); inorganic polymers, such as polysiloxanes, polysilanes, andpolyphosphazenes; natural polymers and their derivatives, such asdextran, cellulose, and carboxymethyl cellulose; and ionomers, such assulfonated polymers (i.e. sulfonated polystyrene) and carboxylicacid-containing polymers (i.e. copolymers of acrylic acid or methacrylicacid). Examples of host polymers also include copolymers of therepeating units of these and other polymers and include mixtures (i.e.blends) of these polymers.

Preferred host polymers include polymers that are conventionally usedfor packaging, either alone or in combination with other polymers.Examples of polymers used for packaging include polyethylene (PE),polypropylene (PP), polystyrene, poly(methyl acrylate), poly(methylmethacrylate), poly(ethyl acrylate), poly(ethyl methacrylate),poly(vinyl alcohol) (PVOH), poly(ethylene: co-vinyl alcohol) (EVOH),poly(ethylene-co-methyl acrylate) (EMAC), polyacrylonitrile (PAN),poly(styrene-co-acrylonitrile) (SAN), poly(styrene-co-maleficanhydride), poly(vinyl chloride) (PVC), poly(vinylidene chloride)(PVDC), poly(ethylene terephthalate) (PET), poly(butylene terephthalate)(PBT), poly(ethylene naphthalate) (PEN), poly(lactic acid), andpoly(glycolic acid). Some of these and other polymers can be used asbarriers materials, especially in multilayer packages. Exemplary barriermaterials include EVOH, PEN, PVOH, PVDC, PAN, and poly(glycolic acid).

The additive compound of the present invention may be mixed with themetal and the host polymer by a variety of methods. For example, thecompound, the metal and the host polymer may be dissolved in a commonsolvent and cast into a film or sprayed onto another polymer as acoating. The solvent may be evaporated to provide a solid material. Thecompound may be added to the host polymer without any solvent, and thetwo components can be mixed mechanically. Mechanical mixing may furtherbe carried out at elevated temperatures by thermal processing techniquesknown to those skilled in the art. The metal can be mixed with theadditive compound prior to contacting the host polymer with theadditive, or the metal can be mixed with the host polymer separately.For example, the metal may be added to the host polymer prior to thecontact between the host polymer and the additive compound, or the metalmay be added to the combined host polymer and additive compound. Theadditive compound and metal may also be mixed together, and this mixedcomposition added to the host polymer.

The combination of the additive compound of the present invention andthe metal, optionally including a host polymer, provides an activeoxygen barrier composition, also referred to herein as the “activecomposition.” For example, an active composition containing a compoundof the present invention and a metal without a host polymer may bedeposited on a polymer substrate. In another example, an activecomposition containing a compound of the present invention, a metal anda host polymer may be formed into a single-layer package. In anotherexample, an active composition containing a compound of the presentinvention, a metal and a host polymer may be formed as a portion orlayer of a package. The active composition may be used alone for makinga polymer-based product, or it may be used in combination with otherpolymers. A host polymer containing a compound of the present inventionand the metal can be blended with a different polymer to form theoverall active composition. The second polymer may contain no additives,or it may contain a compound of the present invention and/or a metal,and the compound of the present invention and/or the metal may be thesame as or different from those present in the original host polymer.The use of polymer blends in packaging materials is described forexample in U.S. Pat. Nos. 6,399,170 B1 and 6,395,865 B2, which areincorporated herein by reference.

When a host polymer is present in the active oxygen barrier composition,the additive compound of the present invention is preferably present inthe active oxygen barrier composition in a concentration from about0.001 percent by weight (wt %) to about 5 wt %. More preferably, thecompound is present in a concentration from about 0.05 wt % to about 3wt %. If a metal is present in the active oxygen barrier polymer, it ispreferred that the concentration be of at least about 30 parts permillion (ppm). If a metal is present, its concentration is from about 30ppm to about 5,000 ppm, even more preferably from about 100 ppm to about3,000 ppm, and still more preferably from about 200 ppm to about 2,500ppm.

The methods and/or processes in which the adhesion-promoting materialproduced and incorporated within the matrix resin and/or barrier resinlayers are disclosed in U.S. application Ser. No. 10/688,432, which isherein incorporated by reference. Likewise, the methods and/or processesin which the active oxygen barrier composition is produced andincorporated within the matrix resin and/or barrier resin layers aredisclosed in U.S. Provisional Application 60/473,024, which isincorporated herein by reference.

FIGS. 3-5 illustrate test results on 400 ml cylindrical containersamples constructed in accordance with the present invention, and FIG. 6illustrates test results on a 10 oz generally cylindrical juicecontainer. FIG. 7 illustrates test results on a 16 oz. cylindricalcontainer. Each container has a five-layer wall ofPET/barrier/PET/barrier/PET configuration. The 400 ml cylindrical testcontainers have a 13 mil nominal sidewall of 3/0.516/0.5/3 mil layerthickness respectively. The preform for the 400 ml container had atwenty-six second cycle production time. The 10 oz juice containers havea 16 mil nominal sidewall of 4.5/0.5/6.0/0.5/4.5 mil layer thicknessrespectively. The preform for the 10 oz juice container had a 25.8second cycle production time. The 16 oz containers have 16 mil nominalsidewall of 4.5/0.5/6.0/0.5/4.5 mil layer thickness respectively. Thepreform for the 16 oz container had a 42.6 second cycle production time.The barrier layer is EVOH, as further described in the respectivefigures. In all tests, the containers are experimental containersconstructed for comparison purposes only. The tests are arbitrarilydevised to obtain differentiation in data and do not reflect anyperformance specification or conditions of use. In FIGS. 3-4, theordinate indicates the percentages of containers in which delaminationis observed by visual inspection. The abscissa identifies containerstructure, specifically the type and total amount of barrier materialand/or active barrier composition by weight. In FIGS. 5-7, the ordinateindicates the dissolved oxygen content (in water) in parts per billion(ppb) measured inside the test container. The abscissa indicates the age(in weeks).

In all of the tests shown in FIGS. 3-7 and Tables I and II, theadhesion-promoting material is a grade SP-012 PEI material marketedunder the trade name EPOMIN by Nippon Shokubai Co., Ltd. This materialhas the following properties according to the resin manufacturer:

Molecular weight 1200 (approx.) Specific gravity 1.05 @ 25° C. Aminevalue 19 mg eq./g solid Freezing point Less than −20° C. Decompositiontemperature 290° C. Flash point 260° C. Amine ratios primary 35%secondary 35% tertiary 30% Chemical Abstract Specification (CAS) No.106899-94-9The grade SP-012 material is stated by the manufacturer to be soluble inwater and alcohol, partially soluble in ethylacetate, THF and toluene,and insoluble in n-hexane.

FIGS. 3 and 4 illustrate side-impact test results on the 400 mlcylindrical containers for non-carbonated and carbonated beverages,respectively. This side-impact testing involves a single impact, at a90° angle, against the container sidewall with a steel wedge and withthe container clamped in stationary position. The energy of the impactis approximately 3.3 joules. FIG. 3 illustrates test results with thecontainers filled with non-carbonated water, while FIG. 4 illustratestest results with the containers filled with carbonated water at 4.2 GV(gas volumes). The barrier resin layers totaled 3% by weight of thecontainers. In the samples having an adhesion-promoting material, theadhesion-promoting material constitutes about 1% of the barrier layerweight. In the samples having an active oxygen barrier composition, thebarrier layer includes about 0.25% of the additive compound and includescobalt neodecanoate (CoNeo) at about 0.25% of the barrier layer weight.Also for each sample containing an oxygen barrier material, the activeoxygen barrier composition comprises a different additive, namely citraldimethyl acetal (CDMA), citral diethyl acetal (CDEA), citral dibenzylacetal (CDBA) and citral digeranyl acetal (CDGA).

In the non-carbonated samples of FIG. 3, the presence of SP-012 improveddelamination performance. In the carbonated samples of FIG. 4, however,the presence of the adhesion-promoting material and/or the oxygenbarrier material (regardless of the type of oxygen barrier material)causes delamination of the multilayered wall to reach 0%, whereas thesample with only the EVOH layer demonstrates a delamination of about10%.

FIG. 5 illustrates the barrier properties as a function of time insealed 400 ml cylindrical containers. The package was filled withnitrogen-purged water, and was induction foil sealed with analuminum-foil based seal. The filled and sealed container was stored atambient conditions of 72° F. and 50% relative humidity. The water in thefilled and sealed containers of FIG. 5 was analyzed for dissolved oxygencontent over time. The oxygen in the water was measured with anORBISPHERE 3600 instrument. FIG. 5 is a graph of the dissolved oxygencontent as a function of time. The ORBISPHERE tests were run on similartest samples used for the side-impact test for determining the percentdelamination of the multilayered wall, with the exception of the EVOHvariable. As shown in FIG. 5, the oxygen content inside the testcontainers for each sample increased over time. However, with theexception of the sample that contained CDGA, the dissolved oxygencontent of all containers was lower than the sample which contained EVOHplus adhesion promoting material only. Thus the barrier performance ofthe containers was enhanced with the other additive compounds.

Table I contains drop impact delamination results for the 10 oz juicecontainers. The containers were filled with 185° F. water and wereimmediately capped with polypropylene closures which were lined with anelastomeric lining material. The capped containers were held for twominutes and then were immersed into cool water so as to cool thecontents to room temperature. The

TABLE I Barrier 18″ Drop 36″ Drop 3% (EVOH F-171 + 2% EPO-012) 0% 0% 3%(EVOH F-171 + 2% EPO-012 + 0% 0% 0.5% CDEA @ 2,500 ppm CoNeo) *Samecontainer as used for O₂ Barrier Testing in FIG. 6containers were removed from the cooling water and were allowed toequilibrate to room temperature (72° F.) for a period of twenty-fourhours prior to testing. The drop impact delamination testing consistedof dropping the containers from a given height onto a hard concretefloor. The base of the containers impacted the floor once and a visualinspection of the container was performed so as to determine thepresence of delamination in any part of the container. Testing wasperformed at drop heights of 18 inches and 36 inches. In these samples,the barrier resin layers totaled 3% by weight of the container. In allsamples, the adhesion promoting material contributes about 2% of thebarrier layer weight. In the sample containing an active oxygen barriercomposition, the barrier layer includes about 0.5% of citral diethyleneglycol and includes cobalt neodecanoate at about 0.25% of the barrierlayer weight. For both sets of containers, there were no noted instancesof delamination at either the 18 inch or 36 inch drop height.

FIG. 6 illustrates the barrier properties as a function of time insealed 10 oz juice containers. The package was filled withnitrogen-purged water and was induction foil sealed with an aluminumfoil based seal. The filled and seal containers were stored at ambientconditions of 72° F. and 50% relative humidity and the water in thefilled and sealed containers was analyzed for dissolved oxygen contentover time utilizing an ORBISPHERE 3600 instrument. The ORBISPHERE testswere run on similar test samples used for the drop impact testing asdescribed in Table I. As shown in FIG. 6, the oxygen content inside thecontainers containing only EVOH and the adhesion promoting materialincreased over time. In the samples containing the adhesion promotingmaterial and the active oxygen barrier composition, the dissolved oxygencontent decreased during the first two weeks and increased very littleduring the first nine weeks and subsequently increased at a greater rateduring the first eleven weeks of the test. Clearly, the barrierperformance of these containers was enhanced with the addition of theactive oxygen composition to the adhesion promoting material and EVOH.

Table II contains side-impact test results on the 16 oz cylindricalcontainers for non-carbonated

TABLE II Non- Carbonated Barrier Carbonated @ 3.0 GV 3% (EVOH F-171 + 2%EPO-012) 0% 0% 3% (EVOH F-171 + 2% EPO-012 + 0% 0% 0.5% CDEA @ 2,500 ppmCoNeo)and carbonated beverages, respectively. The 90° side-impact methodologywas utilized as described and used previously for the 400 ml cylindricalcontainers. Table II contains test results for containers filled withnon-carbonated water and for containers filled with carbonated water at3.0 GV. The barrier resin layers totaled 3% by weight of the containersand the adhesion promoting material constituted about 2% of the barrierlayer by weight. In the samples having an active oxygen barriercomposition, the barrier layer includes about 0.5% of CDEA and about0.25% cobalt neodecanoate (CoNeo). As noted in the table, there was nodelamination observed for either container regardless of whether thecontainer was filled with either non-carbonated or carbonated water.

FIG. 7 illustrates the barrier properties as a function of time insealed 16 oz cylindrical containers. These containers were filled withnitrogen-purged water and were induction foil sealed with an aluminumfoil based seal. The filled and sealed containers were stored at ambientconditions of 72° F. and 50% relative humidity and were analyzed fordissolved oxygen content over time with an ORBISPHERE 3600 instrument.FIG. 7 is a graph of the dissolved oxygen content as a function of time.The ORBISPHERE tests were run on similar test samples described in TableII. As shown in FIG. 7, the oxygen content inside the test containersfor each sample increased similarly over time. The oxygen barrierperformance of these 16 oz containers, which contained the CDEA andcobalt neodecanoate, was much different from the behavior of thisadditive as previously observed in FIGS. 5 and 6, where there was anincrease in oxygen bather performance in reference to containerscontaining only EVOH and the adhesion-promoting material. Although notto be bound by theory, one potential explanation for this anomaly inbarrier performance may be due to the much longer injection cycle timesutilized in making the preforms for the 16 oz cylindrical container(42.6 seconds) vs. the 400 ml cylindrical container (26.0 seconds) and10 oz juice container (25.8 seconds). Potentially, the CDEA may havethermally degraded and/or evaporated during the much longer time in theinjection molding melt phase. Evidence in support of this may be seen inthe barrier performance of the CDEA additive in the barrier performanceof this barrier variable in FIGS. 5 and 6, the containers of which havesimilar injection cycle times. It would appear that the barrierperformance of this variable increases in the example of FIG. 6 wherethe CDEA is added at 0.5% versus that of 0.25% in FIG. 5. In each ofthese examples, the barrier performance is still better than that of thecontainer variable containing only EVOH and the adhesion-promotingmaterial. As such, potentially decreasing injection molding cycle timein producing the preforms for the 16 oz cylindrical containers and/oraddition of a higher quantity of the CDEA would result in increasedbarrier performance for this container example.

There have thus been disclosed a multilayer container, a multilayerperform, a barrier resin blend for use in a multilayer container, amethod of making a multilayer perform or container, and a method ofmaking a multilayer plastic article of manufacture that fully satisfyall of the objects previously set forth. The container, barrier blendand method of manufacture have been disclosed in conjunction with anumber of exemplary embodiments thereof, and several modifications andvariations have been discussed. Other modifications and variations willreadily suggest themselves to a person of ordinary skill in the art. Theinvention is intended to embrace all such modifications and variationsthat fall within the spirit and broad scope of the appended claims.

The invention claimed is:
 1. A composition comprising an active oxygenbarrier composition blended with a barrier resin, the barrier resincomprising EVOH, and the active oxygen barrier composition comprisingpolyethyleneimine and cobalt neodecanoate, and an additive comprisingcitral digeranyl acetal.
 2. The composition of claim 1, wherein thecomposition comprises about 1% by weight of the composition ofpolyethyleneimine, about 0.25% by weight of the composition of cobaltneodecanoate, and about 0.25% by eight of the composition of citraldigeranyl acetal.